Process and arrangement for drainage of wet leather and similar fibrous material



Aug. 25, 1970 DOKOUPlL ET AL 3,525,10

PROCESS AND ARRANGEMENT FOR DRAINAGE OF WET LEATHER AND SIMILAR FIBROUS MATERIAL Filed May 10, 1968 United States Patent Office PROCESS AND ARRANGEMENT FOR DRAINAGE OF WET LEATHER AND SIMILAR FIBROUS MATERIAL Jifi Dokoupil, 38 Opavska, and Jiii Zubik, 16 Hlavni namesti, both of Krnov, Czechoslovakia Filed May 10, 1968, Ser. No. 728,372 Claims priority, application Czechoslovakia, May 12, 1967, 3,437/ 67 Int. Cl. F26b 3/00 US. Cl. 34-6 12 Claims ABSTRACT OF THE DISCLOSURE Wet hides are drained by introducing the hides between two conveyor bands of a resilient and gas pervious material capable to retain moisture due to surface tension, by subsequently applying pressure on said bands from both sides and by final removal of the moisture retained in said conveyor bands by suction, blowing or by dynamic forces.

BACKGROUND OF INVENTION Water from wet hides and similar fibrous material is in the cause of leather treatment generally removed by introducing the hides between two rollers, rotating in the opposite direction, which theoretically are with the hide in contact along a line and which squeeze the moisture out of the hide by pressure. In order to improve the efiiciency of said rollers, they have been provided with a felt lining, which sucked on the surplus moisture. A roller provided with knives has been generally provided in front of the couple of rollers to straighteen the hide and to prevent bent parts of the hide enter between both rollers. In operation such devices are rather inefiicient, as they operate discontinuously and cannot form a part of a continuous production line.

Recently designed continuously operating machines for draining hides introduced the leather between two felt conveyor bands, into which the moisture contained in the leather is transferred by applying pressure on these convenyor bands from both sides, so that the moisture is sucked on by the felt and is retained there due to the capillary effect. A drawback of this arrangement is, that the felt conveyor bands are after passage of a number of hides saturated by water so that they loose their capability of sucking on more water. Removal of moisture from felt conveyor bands is very difficult, due to their high capillary forces. Another drawback of these devices are diffrculties with bent parts of the hides, particularly of thin hides of complicated shapes. As furthermore the felt bands are not resilient, they cannot well adjust their thickness to the thickness of the treated hides, so the central part of the bands becomes stretched and the whole band has to be frequently replaced.

SUMMARY OF INVENTION The drawbacks of actual machines of this lkll'ld are eliminated by this invention which provides a couple of conveyor bands, between which the treated hide is introduced, which conveyor bands are made of resilient, gas pervious material, which offers to passage of air no greater resistance than 1000 mm. of water column per square decimeter and which is capable to retain moisture due to surface tension. Pressure is thereafter applied from both sides of said conveyor bands, whereby moisture from the hide is transferred to said conveyor bands, which moisture is removed from the conveyor bands by suction, by passage of an air stream through the con- 3,525,160 Patented Aug. 25, 1970 The use of conveyor bands having the task of taking along the treated leather through the operating space is necessary as the leather has generally a complicated shape, is rather soft when soaked and a continuous operation would be otherwise rather difficult. The removal of moisture from the leather by applying pressure is at the present state of technique equally the most efficient method. The pressure can be transmitted to the leather either by a couple of rollers rotating in opposite directions, by skids or by intermittent action of reciprocating pressure devices acting on whole surfaces or simultaneously in a number of points or finally by the combination of similar elements. It is however substantial for this invention that the moisture removed due the action of pressure from the leather is transferred to a conveyor band made of a material from which the moisture can be again easily removed in order to be able to proceed continuously with removal of water from another leather piece.

The removal of water from such a continuously moving conveyor band at or near the place where pressure is applied is easy as long as the moisture contained in the conveyor band is retained there predominantly by surface tension and not by capillary action. This moisture can be in such a case removed by the application of suction, by passage of an air stream through the conveyor band or by mechanical action preferably by vibration. The conveyor band has to be made of material showing resiliency at least in a direction perpendicular to the surface of the conveyor band in order to be able of adjustment to leather of different thickness and to return to its original shape after release of applied pressure, it must be furthermore pervious to air to such a degree, to enable the moisture contained therein to be removed by suction, by passage of an air stream or by mechanical action. The conveyor band must form channels where moisture is retained by surface tension, and from which it can be easily removed. Material, which corresponds to these conditions, is for example fabric woven from artificial material, for instance polyamide traded under the name of Lycra.

DESCRIPTION OF DRAWINGS The attached drawings show embodiments of this invention. FIG. 1 represents in elevation an embodiment in which steady pressure is applied on the conveyor band by means of skids with a subsequent sucking of the moisture from the conveyor bands. FIG. 2 shows in top view and cross section a part of a conveyor band composed of fibres indicating the retaining of moisture therein; FIG. 3 which is a continuation of FIG. 1 shows the application of pressure means performing a reciprocating movement and removal of water either by passage of an air stream or by transmitting to the convey-or band reciprocating movements. FIG. 4 shows finally in elevation an arrangement in which the leather with the conveyor bands is bent around an edge.

With reference to FIG. 1 the leather 1 is introduced between two conveyor bands 2, 3, of an elastic and gas pervious fabric made of synthetic fibres, which fabric is resilient at least in a direction perpendicular to the band surface. It could be also made of rubber with a sufficient number of interstices capable of accepting and retaining moisture in these interstices by surface tension. Generally any material should be suitable which shows the above described resiliency perpendicularly to the band surface and the resistance to passage of air in a direction perpendicular to the band surface below 1000 mm. of water column per square decimeter of surface. The conveyor bands are guided by guiding, driving and 3 tensioning rollers 15. Not far from the entrance of the leather 1 between the conveyor bands 2, 3 are pressure means which can be rollers for instance. In FIG. 1 skids 13 are shown, on which pressure is applied either permanently as indicated by arrows 5 or intermittently as indicated by arrows 12 in FIG. 3, where the skids 13 also have an undulating surface. The water is removed from the conveyor bands in FIG. 1 by a suction nozzle 8.

In FIG. 3 in the upper part we see the conveyor band 2 guided over a transfer roller 16 creating a loop of the band 2 with a channel 17 supplying pressure air by way of openings 9 towards the conveyor band 2 where it pushes the moisture from the interstices of the conveyor band 2 into vessels 18 arranged at both sides of the conveyor band 2. The accumulated water is thereafter discharged from the vessels 18.

In the lower part of FIG. 3 the conveyor band 3 is guided over two transfer rollers 19 creating thus a horizontal stretch of the band 3, underneath of which there is the vessel 20, with a reciprocating skid 11 above the bands 3 transmitting to the free horizontal stretch of band 3 a vibrating motion so that the moisture contained therein is removed due to this mechanical effect.

FIG. 2 shows an example of a fabric indicating how drops of water 6 are retained in the interstices between adjacent fibres 4, which form the fabric of the conveyor bands. It is obvious that the moisture is here retained by surface tension of the water.

FIG. 4 shows another embodiment of the invention in which the leather 1 together with both conveyor bands 2, 3 is guided over the edge of a bar 14 forming a bend, where the major part of moisture from the leather 1 is transferred to the conveyor bands 2, 3 and is subsequently sucked off by the suction nozzle 8.

It is of course possible to combine these elements for instance so that the pressure means 13 are represented by reciprocating elements provided with a number of extensions, which transmit pressure to the leather way of the conveyor bands 2, 3 whereby said pressure, elements are contained in housings, where underpressure is maintained, so that moisture transferred to the conveyor bands 2, 3 is immediately sucked off from said bands. The use of reciprocating pressure elements has the advantage of enabling an easy forward movement of the conveyor bands. The use of reciprocating pressure elements enables also a better equalizing of possible bends or wrinkles of the leather.

The above described treatment of leather can be of course repeated if required. The arrangement according to this invention enables thus a continuous and efficient draining of leather and may form a part of a continuous production line.

What is claimed is:

1. A method for continuously draining liquid treated leather or similar fibrous materials comprising the steps of conveying said leather between a pair of opposed pervious conveyor bands capable of retaining moisture, applying intermittent pressure to said moving bands, to transfer the moisture from said leather to said bands and thereafter removing the moisture accumulated within said bands.

2. The method according to claim 1 wherein the moisture of the leather is held on the conveyor bands by surface tension.

3. The method according to claim 2 including the step of passing air through said conveyor to dry said leather and conveyor.

4. Apparatus for the drainage of liquid treated leather comprising a pair of opposed air pervious absorbent conveyor belts adapted to receive and convey said leather therebetween and retain moisture thereon by surface tension, means for applying pressure to at least one of said belts during movement thereof to transfer moisture from said belts and means for removing said transferred moisture from said belts.

5. The apparatus according to claim 4 including means for intermittently and repetitively applying pressure to said bands.

6. The apparatus according to claim 5 including a housing surrounding said pressure application means and a source of suction to provide a vacuum within said housing during the application of said means.

7. The apparatus according to claim 6 including a skid located in contact with the outer surface of said band and means for reciprocating said skid in a direction perpendicular to the movement of said band.

8. The apparatus according to claim 6 wherein said skid is provided with an undulating surface.

9. The apparatus according to claim 4 including jet suction means for sucking said moisture from the surface thereof.

10. The apparatus according to claim 4 including air blowing means for forcing said moisture from the surface of said band.

11. The apparatus according to claim 4 including a series of rollers for moving said bands, said rollers being arranged so as to bend said conveyor bands to remove the moisture therefrom.

12. The apparatus as set forth in claim 4 including means for vibrating said belt during passage of said leather therebetween.

References Cited UNITED STATES PATENTS 2,207,278 7/1940 Albrecht 3495 3,283,415 11/1966 Schnyder 34-111 3,347,740 10/ 1967 Goumeniouk 34111 XR JOHN J. CAMBY, Primary Examiner U.S. Cl. X.R. 34-9, 

